1. Field of the Invention
The present invention relates to cured dielectric films and to a process for the treatment of the surface of such films to remove moisture and other contaminants therefrom. Such treatment is done by electron beam exposure of the dielectric surface in order to prepare it for a subsequent chemical vapor deposition of oxide, nitride or oxynitride layers. These films are useful in the manufacture of integrated circuits.
2. Description of the Related Art
The field of semiconductor technology continually requires the formation of integrated circuit chips having more and faster circuits thereon. Such ultralarge scale integration has resulted in a continued shrinkage of feature sizes with the result that a large number of devices are available on a single chip. With a limited chip surface area, the interconnect density typically expands above the chip substrate in a multi-level arrangement and therefore the devices have to be interconnected across these multiple levels.
The interconnects must be electrically insulated from each other except where designed to make electrical contact. Usually electrical insulation requires depositing dielectric films onto a surface. It is known in the art that a variety of resins are useful in the semiconductor fields to provide a dielectric coating to silicon wafers and other microelectronic devices. Such coatings protect the surface of substrates and form dielectric layers between electric conductors on integrated circuits. Semiconductor devices have multiple arrays of patterned interconnect levels that serve to electrically couple individual circuit elements thus forming the integrated circuit.
In the processing of microelectronic devices, dielectric layers are typically subjected to planarizing and etching treatments and hence adjacent layers are usually separated by an etch stop or other separation layer. Etch stop layers usually comprises an oxide, nitride or oxynitride film such as a silicon oxide film formed using chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD) techniques. However, the application of such films to dielectric layers has become a problem. This is due to moisture and contaminants such as organic solvents, hydrocarbons and stray particles on the dielectric surface.
It has now been found that such moisture and contaminants can be eliminated from the surface of dielectric films by exposing the surface of the dielectric to electron beam radiation. Such electron beam exposure effectively removes these contaminants and allows the surface to more readily accept chemical vapor deposited oxide, nitride or oxynitride films.